I found an 18+ Minecraft Java Edition SMP that is starting a brand new world really soon. It is meant to be survival with adventure and that fresh start feeling where nothing is claimed yet.
They are still voting on whether it will be vanilla or modded. They are also still deciding the PvP and griefing rules. If you join early you actually get a say in how it runs.
The whole point is long term survival with an active community. They want real progression and stories and not a world that dies after two weeks.
Fresh 18+ Java SMP Launching Soon
GG.MINEWIND.NET New Server IPPlayer-Led Nations Roleplay Worldbuilding Server
Crescenta is a player led server that has been running for over 2 years. It is all about worldbuilding storytelling and roleplay with more mature people.
The current world is called Gary and it has been around for 6 months. The goal is to keep it going for years so it still feels like the early days and there is lots of room to grow.
Instead of normal land claims it uses a Citadel style reinforcement system. Your stuff can be protected with block based protection so you do not have to stress about chunk borders.
There are multiple nations with their own traditions politics and cultures. You can join one or try to start your own nation and some groups are willing to share land so new players can get started.
It supports versions 1.21.8 to 1.21.11 and it has Java and Bedrock crossplay.GG.MINEWIND.NET New Server IP